Numerical simulation of the refractive index distribution in a gaseous medium by ray tracing

Aim. To develop and test a numerical method for analyzing optical distortions arising from light propagation through a gas flow with a spatially inhomogeneous refractive index.

Methodology. Numerical simulation of light ray propagation in a gradient medium was performed using the ray tracing method in the ANSYS Zemax OpticStudio software environment. The refractive index distribution was defined by a parametric function. The ray coordinates after passing through the gas flow model were exported and processed in an external Python program to construct displacement fields similar to those used in schlieren methods.

Results. The simulation of light propagation through a thermal plume model was carried out, and the dependences of image displacement on the initial ray coordinates were obtained. The agreement between the numerical simulation results and experimental data is shown. It is established that the observed scatter of points is due to the statistical nature of ray tracing and aberrations of the optical system.

Research implications. The proposed approach allows taking into account the real parameters of the optical recording system and simulating arbitrary refractive index distributions. The method can be used for interpreting data from schlieren experiments and solving inverse problems of reconstructing gas flow parameters. 

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